Awesome! Glad you made this topic. Copying my choices from the status reply but with longer explanations.
- urban streets at night/cyberpunk vibe
This is probably my most favourite setting/theme for a level. It gives me some sort of nostalgia and deep longing. Something with that dark/dangerous near future vibe. Technology, dense urban environment, crime, etc. Best when combined with retro synthwave music.
- ancient ruins, particularly if taken over by nature
I've always been fascinated with the idea of nature taking over long after our civilisation has disappeared, and seeing it represented in games often feels somewhat calming and intriguing. Oftentimes you see a ruined location and you wonder how it might've looked when it was still being used.
- gothic places, like mansions and palaces
These always give me a sort of dark and somewhat romantic feel. Especially when the dark feel of the place is offset by a lot of bright colours that are used in its decoration. And moody music on top.
- sea-related and underwater, but NO swimming sections
I guess it's no secret that the underwater world is a huge mystery to us, and that's what intrigues me about this setting. But also I like the idea of human-made structures being built on or along the sea.
- deep space/aboard spaceship
When done right, it can make things feel extremely isolated, because when in space, you're millions of miles away from any other life. It's both scary and fascinating.
- mysterious, ghost-town like locations which should be busy but are not (e.g. empty cities, schools, hospitals).
What attracts me about these kind of locations is how unusual they are. Normally you see city streets, schools, and hospitals as full of people. So when you see them completely empty with no signs of life, it's very strange and unsettling. With the right atmosphere, it's perfect for horror settings.
I'll post more if I remember.